Share this article

But the manufacturer did not take the device off the market until last year – three years after patients first reported problems.

In another example a retired businessman had to be taken to hospital after his pacemaker mistakenly gave him 30 electric shocks in a day.

Chris Pitt, who is in his 60s and lives in Andover, Hampshire, had the device fitted following a long history of heart problems.

Prompt action: Investigations have been launched into the safety of metal on metal hip replacements with fears growing about the risk of poisoning

But less than a year later it suddenly began giving him electric shocks as if to restart his heart – even though the organ was functioning normally.

Mr Pitt had the device removed and replaced with another pacemaker. He has recovered from the effect of the shocks but is not sure whether they have caused any long-term damage.

The investigation, by the British Medical Journal and Channel 4’s Dispatches programme, also reveals that last year a breast implant that had been used on 40,000 women in the UK was recalled after it emerged it was prone to leaking, and had never undergone safety tests.

Experts say manufacturers are not properly monitoring the safety of their devices and are relying on patients to report any faults.